Vice President Joe Biden (4th r.) speaks during a meeting with victim's groups and gun-safety organizations in the Eisenhower Executive Office Building on the White House complex in Washington Wednesday.

But even before the first session could begin – a closed-door meeting with representatives of gun-control groups and victims of gun violence – Mr. Biden demonstrated why the issue is so fraught. He suggested unilateral action by the White House, stoking long-held fears that Mr. Obama plans to do whatever he can to limit access to firearms and ammunition. Biden’s remark also caused a dip in the stock price of gunmakers and retailers, according to CNN.

"The president is going to act," Biden said to reporters before the meeting. "There are executive orders, there's executive action that can be taken. We haven't decided what that is yet.”

The Drudge Report website responded with this display: “White House threatens ‘executive order’ on guns.” Pictured above were two notorious dictators from the 20th century, Adolph Hitler and Josef Stalin.

The Biden-led task force is the president’s response to the Dec. 14 massacre in Newtown, Conn., which left 20 first-graders and six school staff dead. The lone gunman, 20-year-old Adam Lanza, had used weapons owned by his mother, whom he also murdered.

The mass shooting in Newtown put a range of issues on the table: access to weapons and high-capacity ammunition magazines, mental-health services, school safety, and law enforcement. The Biden effort’s goal is to think broadly across government agencies, consult stakeholders, then present recommendations to the president and Congress for quick action.

In Wednesday’s meeting, gun-control advocates agreed that the nation needs a new ban on assault weapons and high-capacity ammunition magazines, a requirement that all gun purchasers submit to a background check, and improvements in law enforcement, according to news reports.

“There is a powerful consensus building in this country, which is reflected in the meetings of this task force,” Dan Gross, president of the Brady Campaign to Prevent Gun Violence, said in a statement after the meeting. “We are having the conversation the American public wants us to have. Conversations are needed regarding assault weapons, high-capacity magazines, and changing social norms, as well as the very important need for comprehensive background checks – supported by an overwhelming majority of Americans, including gun owners and NRA members."

The marquee event in Biden’s meetings will come Thursday, when a representative of the National Rifle Association (NRA) – the nation’s biggest and best-funded gun-owners’ organization – comes to the White House for the session with gun-rights groups.

“If there’s going to be fireworks, it’s going to be tomorrow,” says Richard Feldman, president of the Independent Firearm Owners Association, who is also coming to the meeting on Thursday.

Some gun-control advocates were unhappy that the NRA was included, but Mr. Feldman calls it a “win-win” for Biden and the NRA. It makes both look open-minded.

Top NRA official Wayne LaPierre made a rare public statement to the press a week after the Newtown massacre, and proposed the government fund the presence of an armed guard in every school. His body language did not suggest a willingness to meet gun-control advocates part way. A different NRA representative will attend the White House meeting on Thursday.

In an interview on NBC’s “Meet the Press” that aired on Dec. 30, Obama did not respond positively to the NRA’s proposal.

“I am not going to prejudge the recommendations that are given to me,” Obama said. But, he added, “I am skeptical that the only answer is putting more guns in schools.”

Another surprise participant in Thursday’s meeting is Wal-Mart, one of the nation’s biggest gun-sellers, which had initially declined an invitation.

“We underestimated the expectation to attend the meeting on Thursday in person, so we are sending an appropriate representative to participate,” David Tovar, vice president of corporate communications for Wal-Mart, said in a statement.

Even though there appears to be little common ground between the gun-control and gun-rights crowds, analysts of gun politics suggest potential areas of agreement. ”We all want to keep guns out of the hands of dangerous criminals and mentally disturbed people,” says Feldman, a former NRA official.

In addition, senior White House staff have already held and will continue to hold meetings with medical groups, community organizations, child and family advocates, business owners, faith leaders, and others on gun violence, White House press secretary Jay Carney said Tuesday.